This invention relates to a shake corrector for use in an optical apparatus, a photographing apparatus provided with a shake corrector, and a shake correcting method.
In recent years, there has been proposed a camera having a function of detecting a shake amount of a camera main body with respect to an object resulting from a shake of a hand by using a CCD (Charge Coupled Device) or the like and correcting this shake amount to cancel it, for example, in Japanese Unexamined Patent Publication No. 8-51566. Further, video cameras, electronic still cameras having a similar function have been commercially available.
The cameral disclosed in Japanese Unexamined Patent Publication No. 8-51566 includes a correction optical system provided along an optical axis of a taking lens and a CCD area sensor for detecting a shake amount. The shake amount of the camera main body with respect to an object is calculated based on a variation of a light receiving position of an object image sensed by a CCD area sensor, and a drive amount by which the correction optical system is to be driven is calculated based on this shake amount. Further, a target position is calculated based on the calculated shake amount in view of a predicted shake, and the correction optical system is controllably driven to the target position in accordance with the predicted shake. On the other hand, a displacement of the target position caused by a variation of an ambient temperature of the camera main body is corrected according to the ambient temperature.
Japanese Unexamined Patent Publication No. 7-306432 discloses a camera which is capable of detecting an ambient temperature and changing a frequency characteristic (filter characteristic) of a servo circuit in order to correct a natural frequency of a feedback loop system which varies according to the ambient temperature.
In the camera disclosed in the Japanese Unexamined Patent Publication No. 8-51566, the correction optical system needs to be controllably moved until the target position is reached while properly following the hand shake. However, the driving performance of a moving mechanism for moving the correction optical system, such as gears, and a motor for providing a driving force to the moving mechanism change according to variations in the ambient temperature. In other words, these members have temperature characteristic. Accordingly, unless the movement of the correction optical system is controlled in consideration of the temperature characteristic of these members, the shake cannot properly be corrected.